Fin structure



March 10, 1959 G. a. BAILEY 2,876,631

FIN STRUCTURE Filed May 24, 1956 IN V EN TOR. GEORGE B. BAILEY BY "Baumbun-7k his ATTORNEYS United States FIN STRUCTURE George B. Bailey,Orange, Conn assignor to John B. Pierce Foundation, New Haven, Conn., acorporation of New York Application May 24, 1956, Serial No. 587,006

7 Claims. (Cl. 62-285) This invention relates to an extended fin surfacestructure adapted to divert liquid condensate forming on the surface ofthe structure to a relatively small discharge area and to collect andcarry off this condensate.

Extended fin-surface structures of many types are commonly employed inheating and cooling systems for residences, ofiices and other livingspace. These structuresconsist generally of a tube for conducting a heatexchange fluid having a plurality of closely spaced fins attached to thetube which serve to improve the heat exchange capacity of the structure.These structures may be used both for heating and for cooling thesurrounding air space. Where employed as heating means, little or nodifiiculty arises from moisture condensation. However, whena coolingfluid is circulated through the tube, the high moisture content of thewarmer air being cooled by this system results in condensation ofmoisture on the surfaces of the fin and requires provision of means forcollecting the condensate and transporting it away from the finstructure to a suitable drain.

The individual fins are fabricated of thin sheets of heat-conductingmaterial and are usually of square, rectangular or circular shape.Attempts have been made to collect condensate by arranging troughsbeneath the fin structure. The trough must be wide enough to collectcondensate from the complete width of the fin structure, and this hashad many disadvantages, In the first place, insuflicient moisture iscondensed to necessitate a large trough. Secondly, .the wide troughseriously impairs the circulation of air around and through the finstructure, thus cutting down on the efiiciency of heat transfer. This isparticularly evident where the extended fin structure is employed inceiling or valance heating where a large part of the extended finstructure is covered by a valance. In addition, such large troughs areexpensive and cumbersome to install and maintain.

An additional problem is that of secondary condensation on the outsidesurface of the condensate troughs which in some cases may requireinsulation.

These problems have been recognized in the heating and air conditioningart and several attempts have been made to correct them. One suchattempt has been the use of a square fin, with one point of the squarearranged at the lowermost point 'of the structure. In this embodiment,it was hoped that the condensed moisture would converge downwardly alongthe tapered edges of the fin to the lower point of the square. Thecondensate would then be collected by means of a small, narrow troughdisposed directly beneath the lowermost point of the fin. In practice,however, it was found that the tapered sides of the fin did notcompletely insure the converging of condensed moisture and much of themoisture dropped from portions of the fin not covered by the narrowtrough.

In addition, elaborate attempts have been made to provide suitabletroughs, some having concentric troughs with insulated portions disposedbetween the two. Troughs have also been disposed beneath the fins by theuse of hangers or similar devices in an attempt to insulate the troughfrom the fin structure. None of the attempts of the prior art, however,has been considered acceptable 2,875,631 Patented Mar. 10, 1959 ice and,although many people prefer the circulating fluid systems employingextended fin surface structures for winter heating of residences, forcedair systems are now more extensively used because they can be used forboth heating and cooling without the above-mentioned disadvantages.

It is therefore an object of the present invention to provide anextended fin surface structure from which condensate may be readilycollected in an inexpensive and efiicient manner without impairing theefiiciency of the fin surface structure.

Another object of this invention is to provide a fin structure of novelshape and surface characteristics which serves to direct condensedmoisture thereon to a discharge point on the lowermost part of the finstructure.

Another object of this invention is to provide a condensate trough whichmay be attached directly to a plurality of fins of an extended finsurface structure and which remains substantially free from secondarycondensation in use. I

These and other objects of this invention are accomplished by providingan extended fin surface structure with fins, each fin having a shapesuch that one or both sides are tapered angularly toward a point at thelowermost extremity, and by providing each fin with a roughened surface.A fin of this shape, with surface properly roughened, insures that themoisture formed by condensation on the fin surface will be as a thincontinuous film of condensate on the fin and will gravitate to thelowermost and relatively narrow discharge portion of the fin, where itmay be collected in a narrow trough.

It has also been found advantageous to dispose a light 7 weight plastictrough directly beneath the narrow discharge portion of the fins and toattach this trough to the lowermost portion of each fin by providingslots in the sides of the fin to receive supporting edges formed on thetrough. The slots are preferably formed at an angle directed downwardlyfrom the tapered sides toward the opposing side of the fin. When thetrough is attached in place, the supporting edges of the trough extendoutwardly beyond the edge of the fin, to insure collection of all of thecondensate. The trough is preferably resilient so that it may beextended laterally and attached by clipping. Where the trough isattached to every fin of the extended fin surface structure, the troughdoes not sag and efiicient collection of condensate is assured from eachfin surface. The plastic material is preferably non heat-conductive,which substantially eliminates the problem of secondary condensation.

In order to insure that all of the moisture condensed on the fin surfacewill gravitate to the lowest point on the fin and thus into the trough,the fin surface must be roughened. The reason for this is that in thecase of the smooth or polished fin surface of aluminum or copper sheetsfurnished from the mill, condensed moisture forms in drops and, althoughmost of the drops so formed gravitate to the trough as a result ofcohesion to the surface, a few of them do not. However, it has beenfound that roughening the surface causes the condensed moisture to forma film on the surface of the fin rather than drops. The film adherescompletely due to surface tension and all of the condensed moisturegravitates to the low point of the fin and into the trough. Rougheningof the fin surface can be easily and inexpensively accomplished by wirebrushing or bufiing with a revolving wire brush or by dipping thesurface in a chemical solution which will pit the fin surface. Forinstance, it has been found that a 5 to 10% solution of sodium hydroxidewill result in a very rapid action of pitting the surface of aluminumfins or sheets.

Where these improved fin surface structures are employed in a ceiling orvalance-level heating and cooling system, the structure preferablyincludes a metal valance cover adapted to clip on to the extended finsurface structure and trough to provide an extremely simple, inexpensiveand decorative cover for the extended fin surface structure. The covercomprises generally a body portion adapted to conform to the shape ofthe individual fins and has at one end a flange adapted to be receivedin and engaged by a slot formed in the upper surface of each fin. Thelowermost portion of the cover is shaped to conform to the externalsurface of the trough and extends about the trough to form a positiveengagement therewith. The cover is attached by simply placing the flangeon its upper portion in engagement with the plurality of slots on theupper surface of the fins and by clipping the lowermost portion aroundthe trough member attached to the fin.

These and other advantages of the invention will be more readilyunderstood when the following is considered in connection with theaccompanying drawings in which:

Figure l is an elevation showing one embodiment of the novel finstructure of this invention;

Figure 2 is a cross section of a trough according to this invention; I

Figure 3 is an elevation showing the novel fin structure with troughattached;

Figure 4 is a perspective view of the extended fin surface structure ofthis invention with trough attached, showing the arrangement of thevarious components in cluding the preferred valance cover; and

Figure 5 is an elevation of the fin surface structure of this inventionwith the trough and valance cover shown attached in cross section.

Referring to the invention and in particular to the embodiment shown inFigures 1, 3and 4, a tube adapted to conduct a heat transfer medium isprovided with a series of thin sheet metal fins 11. The fin 11 as shownin Figure 1 has tapered portions 12 and 13, the angle 14 of the taperedportion with the vertical line 15 being 30 degrees. A pair of slots orindentations 16 are disposed in the tapered portions 12 and 13 and aredownwardly inclined from the horizontal toward the center of the lowerpoint of the fin 11.

The trough 17 shown in Figure 2 is of semi-cylindrical shape and has apair of depending supporting edges 18 arranged to be received in slotsor indentations 16 of the fin 11. The trough 17 is of resilient plasticmaterial and may be easily clipped on or removed from slots 16 .of finl1.

The valance cover means 19, as shown in Figure 4, comprises a flange 20on its upper end disposed on an arm 21 of the cover 19. The flange 20 isreceived in slots 22 provided in the upper surface of the fins 11. Themain portions 23 and 24 of the cover 19 are arranged to substantiallyconform with the shape of the fin 11. The lower portion 25 is adapted toengage the trough 17 and is shaped to substantially conform to thecircular shape of the trough 17.

The surface of the fin 11 in the embodiment shown in Figure 3 has beenroughened, as indicated, by dipping the surface thereof in a 10%solution of sodium hydroxide. The fins 11 of Figures 1, 2 and 4 havebeen similarly roughened by bulfing with a revolving wire brush.Treatment of the fins 11 in this manner permits the moisture to condensein the form of a thin film rather than as discrete droplets, and thesurface tension of the film insures that the moisture gravitates to thecollecting trough 17.

From the above description, it will be apparent that the moisturecondensed on the surface of tin 11 when the extended fin structure isemployed as a cooling element will be directed to the center andlowermost portion of the fin, where it may easily be collected in anarrow trough. The extended fin surface structure may-be installed inthe usual manner either by peripheral installation at the ceiling or atthe floor level. Where the'structure is installed in a ceiling orvalance level heating and cooling system, the narrow width of the troughallows increased Girculation of air through and around the fin structurein spite of the necessity of providing a valance in front of thestructure to conceal it from view.

It will be understood that the above-described embodiment of theinvention is illustrative only and that modifications will occur tothose skilled in the art. Therefore, the invention is not to be limitedto the specific apparatus disclosed herein but is to be defined by theappended claims.

I claim:

1. An extended fin surface structure comprising a tube adapted toconduct a heat exchange fluid, a plurality of substantially verticalfins attached to said tube, each fin being tapered in width downwardlyfrom its outermost extremity toward the center of the lowermostdischarge portion of the fin, and each fin having a roughened surfacethereon to insure condensation of moisture in a thin film, a slotentering each edge of each fin at an angle downwardly inclined from thehorizontal and a trough extending the length of the structure, saidtrough having supporting edges adapted to be received by the slots insaid fins, and said supporting edges, when in place, extending slightlybeyond the edges of the fin to insure collection of all condensed liquidgravitating from the fin.

2. The extended fin surface structure of claim 1 wherein the trough isunitary and of resilient material so that it may be removably fastenedto the fins.

3. The extended fin surface structure of claim 1 wherein the structureis provided with a valance cover comprising a body portion, a flange onthe upper edge of the body portion, and a lower portion, said lowerportion being adapted to clip on to and frictionaily engage the trough,and said body portion substantially conforming to the outer edge of thevertical fins.

4. An extended fin surface structure comprising a tube adapted toconduct a heat exchange fluid, a plurality of substantially verticalfins attached to said tube, each fin being tapered in width downwardlyfrom its outermost extremity toward the center of the lowermostdischarge portion of the fin, a slot formed in each edge of each fin,and a trough extending the length of the structure, said trough havingsupporting edges adapted to be received by the slots in said fins, andsaid supporting edges, when in place, extending slightly beyond theedges of the fin to insure collection of all condensed liquidgravitating from the fin.

5. The extended fin surface structure of claim 4 wherein the trough isunitary and of resilient material so that it may be removably fastenedto the fins.

6. The extended fin surface structure of claim 4 wherein the structureis provided with a valance cover comprising a body portion, a flange onthe upper edge of the body portion, and a lower portion, said lowerportion being adapted to clip on to and frictionally engage the trough.

7. An extended fin surface structure comprising a tube adapted toconduct a heat exchange fluid, a plurality of substantially verticalfins attached to said tube, each fin being tapered in width downwardlyfrom its outermost extremity toward the center of the lowermostdischarge portion of the fin, a slot formed in each edge of each fin atan angle downwardly inclined from the horizontal, and a trough extendingthe length of the structure, said trough having supporting edges adaptedto be received by the slots in said fins, and said supporting edges,when in place, extending slightly beyond the edges of the fin to insurecollection of all condensed liquid gravitating from the fin.

References Cited in the tile of this patent UNITED STATES PATENTS

